Adjustable enhanced photoluminescence in whispering-gallery-mode microdisk arrays

Microdisk with whispering gallery modes (WGMs) is a prominent candidate for the studies of fundamental properties of cavity quantum electrodynamics (CQED) and the explorations of on-chip light sources or sensors. Here, we report on the significant array effect on WGMs in SiGe microdisk arrays. Systematic photoluminescence spectra demonstrate an optimal microdisk interval associated with wavelength and the array symmetry dependence for each WGM. The enhancement factor of WGM can be increased by over 270% and 120% with the modification of microdisk interval and array symmetry, respectively. Moreover, a single dominant WGM can be achieved in the array of microdisks with intentionally designed nanoholes. The intrinsic mechanism of the array effect is disclosed in terms of the intradisk light field distribution and the interdisk coupling. Our results provide strategies for the substantial enhancement of desired WGM in microdisk array to comprehensively understand CQED and fabricate innovative optoelectronic devices.